Cooler, wetter weather creates explosive herb growth

Hardy drought- and-heat tolerant herbs became landscaping staples during the past four dry years. Most herbs survived severe drought conditions well, but this year’s wetter, cooler weather has revealed some problems with the herbs in our gardens.

The first and most obvious problem is size. Herbs, especially the Mediterranean varieties, thrive in our dry, arid climate but their growth is usually moderated by limited rainfall and high heat. Many herbs have had a really strong growth spurt this stormy spring. Perhaps the very drought-tolerant Spanish lavender planted by the front door four years ago remained its minimal size of one and a half feet tall and wide during the drought and is now suddenly 3 feet tall and wide, blocking the walkway. What’s to be done with a flourishing herb that’s now too big for the space?

Before buying landscape herbs, check labels for size at maturity and plan on the plant reaching its maximum size within a couple of years. The Spanish lavender that’s now too big for the space by the front walkway may need to be replaced with a smaller, less-invasive English variety.

The size of herbs can be controlled with pruning. Wait until after flowering to prune back overgrown branches on herbs like rosemary which have a short bloom season; cut back wayward branches that encroach on yard space on long-blooming sages/salvias at any time during the summer and give them a hard pruning to six inches high in late winter. Remove lavender flower spikes after bloom but do not cut into the woody tissue below the spikes; hard pruning of lavender deforms its natural shape. All lavender plants tend to become rangy and woody after a few years plan on replacing lavender every two to three years.

Premium content for only $0.99

The second problem is location. Aromatic, flowering herbs attract bees and other pollinators. This year’s extra rain has encouraged a great exuberance of flowers that attract even more bees to our gardens. As an example of a poor location consider the wooly thyme planted as a ground cover between the pavers near the pool. This spring the thyme will be entirely covered with tiny pink flowers, and bees. Most landscape herbs are bee-friendly and should not be planted near high traffic areas or children’s play areas to reduce the possibility of bee stings.

Many herbs do not tolerate overwatering; their roots rot easily and the plants quickly die. Rosemary and lavender are especially susceptible to root rot. When planting herbs into your landscape try to group them in separate irrigation zones according to their water needs and avoid planting thirstier plants in the same location.

Note: the Fresno County Master Gardeners’ annual Spring Garden Tour takes place on Saturday, April 29, this year. Six residential gardens will be open for tours as well as the Master Gardeners’ demonstration garden, the Garden of the Sun, at 1750 N. Winery in Fresno. All the gardens will be open from 9 to 5 that day, rain or shine, and Master Gardener docents will be on hand to gladly answer any gardening questions. (Note: The original version of this column incorrectly reported that the date is April 27.)

Check the tour website, www.ucanr.edu/2017sgtfresno, for descriptions of the gardens, detailed maps, and plant lists for each garden and the plant sale at the Garden of the Sun.

Tickets are $30 in advance or $35 at the gardens on the day of the tour (you can start the tour at any of the gardens).